本文提出了一种新型单路长途电话计费器,此计费器采用8031为处理器,通过监测电话线路,可判断出被叫号码(包括脉冲和双音多频DTMF两种制式)、通话起始时刻,并可计算、打印通话费用。由于此计费器可以在无反极信号的情况下判断出通话起始时刻,因此此种计费器较其它计费器有它自己的优点。 This paper presents a new single long-distance telephone meter, the meter uses the 8031 ​​as a processor, by monitoring the telephone line, you can determine the called number (including pulse and dual tone multi-frequency DTMF two formats), call Starting time, and can calculate, print call costs. Because this meter can judge the call start time without reverse signal, this kind of meter has its own advantages over other meters.